I'd recommend not travelling through Manchester Airport then, which have backscatter machines in place and do not allow for opt-out (although this is as-per DfT guidelines). They do only test a random sample, however.
The Department for Transport has full confidence in the independent assessment
undertaken by the Health Protection Agency. We are confident with their assessment
that the dose from being scanned is far below the allowed levels in the UK and
does not constitute any unacceptable risks to health
